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Wednesday, April 17, 2013

Sanding, Materials, Parts and Supplies

The mizzen boom is nearing its final rounded shape. I knocked off the edges of yesterday's octagon, creating a roughly 16-sided shape. Then the question was, "How do I sand it round?" There are many answers to that question and good - but somewhat inconsistent - information is available on the WoodenBoat Forum. One of the more popular methods involves turning a belt sander belt inside out and powering it with a hole saw chucked into a cordless drill (sorry, that's the short version and not altogether clear). But, I experimented with that method when I built the oars for Karen Ann and I couldn't turn the sanding belt inside out… So, I decided to go lower tech with another sanding method described on WBF.

I cut a short length (about the length of a sheet of sandpaper) of 1½" PVC pipe in half lengthwise. Using double-backed tape, I taped a piece of 80 grit sandpaper to the inside of the PVC and began sanding the mizzen boom. This tool works well - and will work even better with coarser sandpaper for the initial sanding. Later I will work up to 150 grit paper to prepare the boom for varnish. For larger spars I'll use larger diameter PVC.

The blank for the boomkin is glued up and ready for milling.

Thinking about materials for the mizzen mast, I wasn't sure where I'd find 14' stock - without going back to LL Johnson for cvg DF - as the big box stores around here don't carry 1x stock in 14-foot lengths. When I built Karen Ann's mast I used pinus radiata (Monterrey Pine) ordered from the local contractors' lumber yard. This morning when I went in to order the Monterrey Pine, the counterman drew a blank. He just didn't know what I was talking about - and the guy who helped me previously wasn't in today. When I told the guy I'm building spars for my sailboat, he suggested I look at the clear white pine they have in the shed. I'm not sure what the differences are between Monterrey Pine and clear white pine, but the clear white pine is very nice, clear, not-quite-vertical grained. It comes in 10, 12, 14 and 16-foot lengths. I can use this for the mizzen mast and the main yard. I didn't have my roof racks on the Volvo so I'll have to pick up the lumber in the morning.

A quick trip to the Woodcraft Store in Grand Rapids resulted in new tires and guide blocks for the bandsaw, shop-vac fittings to use the dust port on the bandsaw and some tips for refurbishing my Stanley No. 5 Jack plane. I need the plane to be functional but not restored to as-new condition. So, it was a successful shopping trip. I'll get to work on the plane as I want to use it to work on the main mast next week.

Tomorrow will be another busy day: picking up lumber, installing the new tires on the band saw, sanding the mizzen boom (will pick up 50 or 60 grit sandpaper), gluing up the blank for the main yard and milling the boomkin.

2 comments:

Hi Bob,Thanks for explaining the sanding method with half pvc pipe. Now I can go straight to that method as the drilling-chuck thing is a waste of time. Did you glue the paper to the pipe?I have used a planer in the past also and it worked very well. A low angle plane gets to pretty round surfaces. Pine seems to be pretty good for spars. I made a solid mast from laminating 3 1x3" cut pieces, about 8 ft long for Nemo and tapered it at the end. Painted it with brown varnish-stain, alkyd based, and it looks pretty salty to me.

I've tried that drill chuck/sanding belt thing without success, too. The PVC pipe works well (at least so far, haven't tried it on a larger spar) for me. I used one piece of double-back tape run down the center of the PVC, sorta curled the sandpaper and pushed it down against the tape. I cut the sandpaper to the size of the pipe.

I suggest 50-grit or, possibly, 36-grit to begin with and then move up to 80, 120 and maybe 150-grit paper.

Use the PVC pipe closest to the spar diameter.

I've seen instances of handles being screwed to larger PVC pipe for easier handling of the larger sizes. I'll probably try that when I get to the main mast.